Rotor equipped aerial device



April 27, 1948. K. P. SYNNESTVEDT 2,440,295

ROTOR EQUIPPED AERIAL DEVICE Filed May 5, 1944 5 V INVENTOR KENNETH R 5YNN$TVEDT m y d ATTORNEY;

Patented Apr. 27, 1948 ROTOR EQUIPPED AERIAL DEVICE Kenneth P. Synnestvedt, Bryn signor to Autogiro Company of Athyn, Pa., as- America, Philadelphia, Pa., a corporation of Delaware Application May 5, 1944, Serial No. 534,248

1 Claim. 1

This invention relates to rotor-equipped aerial devices, and while not in all respects limited thereto it has especial advantages in connection with aerialdevices adapted to be dropped froman altitude and to descend approximately vertically under the retarding influence of a sustaining rotor.

Broadly considered, the invention has in view the-adequate control ofthe flight path of the device, and the adequate protection of the contents of the device.

One of the-primary purposes of the present in- :vention is to .provide an improved device of the character mentioned, particularly from the standpoint of control.

Another important object of the invention is to provide such a device wherein the body contains an armor-housed space suitable for the enclosure of explosives, or an occupant, or other cargo; and in this regard the invention contemplates the construction and adaptation of the device as an armored parachute, which, according to a further feature of the invention is controllable by the occupant, within limits.

Still further, the invention contemplates a device of the above mentioned character, having cushion means to take the impact of the landing, :and in the preferred embodiment having a door and suitable observation openings or windows.

More specifically, the invention contemplates an aerial device having a body adapted to carry a load, particularly for the purpose of controlled descent when dropped from an altitude, wherein said body is of generally elongated or cylindrical :form, with its long axis approximately upright, the body being provided with a sustaining rotor adjacent the normally upright end and centered approximately on said axis, and in the preferred form also supplied with external finning, preferably controlled from within the body for regulation of the descending flight path.

How the purposes of the invention are accomplished will be apparent from the following description, taken together with the accompanying drawings which illustrate the present preferred embodiment of the invention, and a modification.

Of the drawings:

Figure l is a plan view of one form of the aerial device of the present invention, showing the body thereof, the controllable finning thereon, and the sustaining rotor (the blades of which are partly broken away in this figure);

Figure 2 is a vertical section through the device of Figure l, with the rotor and certain other parts shown in elevation; and

Figure 3 is a fragmentary view similar to Figure 2, but illustrating a second embodiment or modification of the invention.

In Figures 1 and 2, I have illustrated an upright elongater body 5, which may enclose an armored space or may be enclosed by armor, although in the embodiment shown the body itself comprises the armor plate, which is formed to a cylindrical contour. The cylindrical body has a flat lower end face 6 and a generally conical upper end I, the latter being provided with a bearing housing 8 having a central aperture wherein the rotor hub 9 is mounted by means of ball bearings I I.

The rotor hub 9 .has upstanding ears or lugs l2, apertured to receive a flapping pivot I3 which serves to mount a pair of blade forks M, which latter are integral parts of fittings I5 to which the elongated aeroform blades l6 are attached.

Although it may be power driven, the rotor as shown is mounted and arranged for free rotation under the influence of the air-stream encountered when the device is allowed to fall through the air, for example by being dropped from an aircraft. The aerofoils l6 have their profiles so oriented that the rotor tends to rotate aerodynamically in the direction of the arrow R, when the device is falling; and to assist in initiating or maintaining such aerodynamic rotation, the axis of the flapping pivot I 3 (on which the two blades may individually flap independently of each other) is set at an angle to the longitudinal axes of the blades, so that as the blades cone upwardly their mean geometric pitch angle is reduced, pref erably attaining a negative value when the coning angle is large.

The weight, length, area, and other proportions of the rotor blades, as well as their constructional incidence setting, may be determined by known procedures, according to the load to be carried, the desired or permissible speed of descent, and other operating conditions.

For purposes of cushioning the landing, particularly when the device is designed for use as a parachute, the lower end of the shell 5 is surrounded by a cup-like telescoping member ll, which is normally held in the most extended position, i. e., with the shoulder l8 on the cup abutting against the shoulder ['9 of the shell, by means of a coil spring 2!. To dampen the action of the alighting cushion, and thus to prevent excessive rebound after the device strikes the ground, the cup member I l'may be provided with one or more orifices 22, of such restricted total area as toaccompllsh the desired degree of damping, with relation to the weight of the device, its speed of descent, and the strength of the spring.

When used as a parachute, the cylindrical shell 5 is preferably formed to such a size and shape as to take a man in a standing or sitting position, and in the latter case a suitable seat 23 may be provided. In cases where the body provides a substantially complete enclosure (as in this instance) ingress and egress may be provided by any suitable door or escape hatch 24, and means of observation may be provided in the form of windows 25 and 26, so that the occupant may steer the device, by the means now to be described.

A pair of fixed stabilizing fins may be provided at diametrically opposite points, one of sired rate of speed and. for a cushioned landing; and. in case of the use of armor plate as illustrated, the device protects against small-caliber gunfire.

The control lever 3'! may be operated by some automatic mechanism, for instance by a remote control unit housed in the body and actuated for example by known radio control means, or (as here shown) it may be controlled manually by an occupant, and in this way the device can be (within limits) steered to a desired point of landing. With these capabilities, many uses for the v device will be apparent to those skilled in the these being indicated at 21 in Figure 2. A third stabilizing fin 28 may extend at right angles to the first two, together with finning 28a. Above the stabilizing surfaces 21 and 28 are arranged controllable fins or surfaces 29, 23, and 3i.

Any tendency of the body to rotate about its own axis may be counteracted by suitably regulating the inclination of the fin 3i about its pivot 32. The general descending flight path of the device may be regulated by varying the angular position of the two fins 29, simultaneously in the same sense, about their common pivot axis 33.

For control purposes, an arm 34 is fixed on the cross-shaft 33 and has its free end connected by a link 35 with the short arm 36 of abell crank, the longer arm 31 of which extends downwardly to a position for convenient access by the occupant. This bell crank is pivoted at 38 in the forked end of a rotatable'shaft 39 which is mounted in suitable bearings 4|. The other end of the shaft 39 carries an arm 42 coupled by a link 43 with an arm 44 which lies in a plane at right angles to the arm 34 and is fixed on the pivot pin 32 of the fin 3|. Preferably the control shaft 39 is in a laterally centralized position, extending fore-and-aft (i. e. in the vertical longitudinal mid plane which contains also the fin pivot axis 32 and the rotor axis), and the control arms 42 and 44 extend laterally to the right of the said mid plane. To secure the necessary flexibility in the control connections, the vertical links 35 and 43 preferably have their upper and lower end connections made by means of ball or other angling joints.

By the system just described, a forward push upon the arm or stick 31 (forwardly away from the occupants seat 23) causes a rearward inclination of the two fins 29, which by virtue of the impact of the air-stream thereon tends to tip the upper end of the body forwardly which thus also tips the axis of the rotor in that direc tion, thereby giving a component of thrust in the same direction and causing the device as a whole to travel in that direction. The orientation of such directional motion, with reference to the surface of the earth, may be altered, by turning the body in one direction or the other about its major axis, by means of tilting the stick 31 laterally in either direction, which causes a defiection of the fin 3|, thereby rotating the body about its axis, by virtue of the air-stream impinging upon said fin 3 l This same fin may of course be used to arrest rotation, if any undesired rotation should be set up.

From the foregoing it will be seen that whether an occupant or a cargo load is being carried, the device provides for safe descent at any deart.

Turning now to the form of device shown in Figure 3, it will be observed that the body 5 has 7 (as in the first storm) fixed finning 28, 28a and a generally upright surface 3| movable about a horizontal axis 32 which approximately intersects the axis of the rotor; the latter (as before) comprising blades l6 secured to the hub 9 by fittings l5 and a flapping hinge [3. The controls in this embodiment are, however, different from those in the first embodiment, as will hereinafter appear.

The hub bearings ll journal the rotor in a ring 45 which is pivoted by trunnions 46 in a second ring 41, the latter being pivotally carried on upstanding ears 48 of the body by means of trunnions 49 located on an axis at right angles to the trunnions 43. By means of this mounting the rotor axis and thus the rotor thrust line can be tilted in all directions relative to the center of gravity G of the device, a control stick to being coupled to the control ring 45 for this purpose. Considered with relation to the stabilizing and controlling finning, it may be said that the rotor thrust line is shiftable laterally and longitudinally with respect thereto.

The inclination of the fin 3i about the axis of pivot 32 can be varied by a lever 5| which is fixed on pin 32. A restraint, in the form of a fixed rubber block 52 frictionally engages the lever or handle 5|, and thus normally acts to hold the surface 3| to a given setting.

With respect to the blade pitch angle to be employed, it may be said that appreciable variation is permissible. An appropriate autorotative setting found suitable for the purpose is about 4 or 5 degrees above the no-lift setting calculated with reference to a plane perpendicular to the axis of rotation.

The arrangement of Figures 1 and 2 has the advantage of requiring only a single control member and also a simpler rotor mounting. The arrangement of Figure 3, however, gives a more effective control in devices adapted for exceptionally slow descent; and in this form, although the rotor mounting is more complex,'the control connections themselves are simplified. Considering the device as a Whole, both embodiments fu1 fill the purposes set out at the beginning of this specification, and have numerous other advantages which will be apparent to those skilled in the art.

I claim:

An aerial device adapted to be launchedfrom an aircraft in flight comprisinga body, a sustaining rotor having free-flapping airfoil blades to provide for retarded descent of the device, and rotor mounting means, the rotor being rotatively journaled on the mounting means, and the mounting means being attached to the upper end of the body in a manner to provide for universal angular displacement of' the rotor 'axis with respect to the vertical axis of the body portion; and control means comprising a control member extending downward into the body portion, the upper end of the control member being rigidly associated with the rotor mounting means; and further control means comprising an external fin mounted in a plane passing through the rotational axis of the rotor and movable about an axis substantially perpendicular to the vertical axis of the body, and a second control memloer inside the body portion to control the rotation of the fin on its axis.

KENNETH P. S YNNESTV'EDT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name 1 Date Dees July 18, 1916 Freeman June 29, 1920 Wagner Nov. 20, 1928 Gambarini May 12, 1931 Taylor June 23, 1936 Fry Oct. 27, 1936 Wilford Jan. 19, 1937 Bennett Jan. 18, 1938 

